FR2725043A1 - WIDE ANGLE ZOOM TYPE OBJECTIVE - Google Patents

Abstract

The present invention relates to a zoom for a photographic camera. The zoom has a first group of lenses (I) having positive convergence, a second group of lenses (II), and a third group of lenses (III) having negative convergence, the distances between the first group of lenses, the second lens group, and the third lens group being variable during zoom operation. The first lens group (I) has a first lens (1) having a negative convergence and a concave meniscus shape towards an object, and a second lens (2) before a positive convergence and a convex plane towards an object. 'an image plan. The second lens group (II) has a first lens subgroup (3, 4, 5, 6) before positive convergence, and a second lens subgroup (7, 8) having positive convergence towards the object.

Description

The present invention relates to a wide-angle zoom system designed for

  a shutter camera and more specifically a lens

  wide-angle zoom having three groups of lenses.

  The wide-angle zoom lens has a zoom ratio of more than 2.5 times while remaining wide-angle at

from a wide-angle position.

  A normal focal length lens has a focal length approximately equal to the length of

  the diagonal of the recorded image. So in an appa-

  still image photographic reil, a 50 million lens

  Limneters is generally considered an ob-

  normal jective for a 35 mmn film which has a diameter

  negative of approximately 42 mm. An objective

  wide-angle lens has a shorter focal length than an

  normal lens, while a long or telephoto lens

  has a longer focal length than a normal lens.

  In a zoom system, the overall focal length can be adjusted, the largest angle of view being obtained at the shortest focal length and the narrowest angle of view being obtained at

  longest focal length level.

  Shutter cameras have recently become compact and automatic. Shutter cameras are also better suited for

  using a wide-angle zoom. The cameras-

  shutter graphics should be compact, bright, and inexpensive, especially since they are often

  used by non-professionals.

  When the cameras shutter-

  become more compact, the zoom should then become

  more compact. Recently, goals with great-

  angle of view have become popular as have

  panoramic photographic reils. A photograph by

  noramic is taken with a wide-angle view in the

horizontal direction.

  Non-Japanese patent publications

  examined with the numbers Sho 63-16 142 and Hei 5-19 166, both entitled "Wide Angle Zoom" describe zoom lenses comprising a first group of lenses having positive convergence and a second group of lenses

  having negative convergence towards an object.

  On the other hand, the publication of the unexamined Japanese patent bearing the number Hei 4-165 319 describes a zoom comprising a first group of lenses having positive convergence, a second group of lenses having positive convergence, and a third group of lenses with negative convergence in direction

  of an object. Also, the publication of the Japanese patent no

  examined with the number Hei 4-97 112 describes a zoom

  comprising a first group of lenses having a contact

  negative vergence, a second group of lenses having

  a positive convergence, and a third group of len-

  pins with negative convergence towards the object. In the zooms mentioned above, comprising two groups of lenses, the change in magnification of the second group of lenses becomes significant when the zoom ratio is multiplied by three. The significant change in the magnification of the second group of lenses

  strongly increases the modifications of the aberrations

  when the zoom is operated. So the compensation of

  aberrations becomes very difficult.

  It is possible to obtain a large rear focal length at a wide-angle position since it is easy to constitute a retrofocus type lens at the wide-angle position in the zoom consisting of the first lens group having negative convergence, the second lens group having positive convergence, and the third lens group having negative convergence in the direction of

  the object. On the other hand, it is disadvantageous to make

  bearing the total length of the optical system because it is difficult to constitute a system of the type

  the lens at a telephoto position.

  It is difficult to establish the objective of the

  retrofocus type having a large rear focal length

  aunt at the wide-angle position in the zoom consisting of the first group of lenses having positive convergence, the second group of lenses having positive convergence, and the third group of lenses having negative convergence towards the object . In addition, it is difficult to obtain a distance

  rear focal length sufficient to mount a photo-

  panoramic graphic at large position

  angle because the distance between the second lens group and the third lens group at the wide-angle position is increased. It is also difficult to compensate for aberrations beyond an optical axis, caused when light passing through the second lens group passes through a position higher than the optical axis of the third

group of lenses.

  However, the retrofocus type lens having the large rear focal length can be formed when the combined focal length of the first group of lenses becomes the focal length having convergence

  positive, using a lens having two sides

  cellars and having a short focal length with a con-

  negative vergence, in the zoom mentioned above having

three groups of lenses.

  As described above, the shorter the length

  focal lens lens of the first group of lens

  tilles with negative convergence, the more the construction

  tion of the retrofocus type lens is advantageous.

  But at the same time, it's a disadvantage to have a

  important riation of the aberrations of the first group of

  lenses because the focal length of other lenses

  tilles having a positive convergence of the first group

of lenses should be short.

  It is possible to obtain a large rear focal length at the wide-angle position since it is easy to constitute the retrofocus type lens at the wide-angle position in the zoom consisting of the first group of lenses having negative convergence, the second group of lenses having positive convergence, and the third group of lenses having negative convergence towards the object. On the other hand, it is a drawback to make the total length of the optical system large because

  that it is difficult to constitute the system of the type

  the lens at the telephoto position.

  The present invention overcomes the problems and

  the disadvantages of the prior art in providing

  sant a compact zoom system which uses a first group of lenses having a concave meniscus lens

  towards an object and two lenses having a con-

  positive vergence towards the object, and a third

  sth group of lenses having a short length fo-

  negative wedge in the zoom made up of a first group of lenses having a positive convergence, of a

  second group of lenses with negative convergence

  tive and a third group of lenses having a con-

positive vergence.

  To achieve the goals, and in accordance with the

  the present invention, as embodied and widely described herein, the wide-angle zoom system

  comprises a first group of lenses having a conver-

  positive gence, a second group of lenses, and a

  third group of lenses with negative convergence

  tive. The distances between the first group of

  lenses, the second group of lenses and the third

  sth lens group are changed during the ac-

  zoom. The first group of lenses

  wears a first lens having negative convergence

  tive, having the shape of a concave meniscus lens in the direction of an object and a second lens having a positive convergence and a convex plane in the direction of the image plane. The second lens group includes a first lens subgroup having positive convergence toward an object and a second lens subgroup having positive convergence toward an object

of an object.

  The wide-angle zoom system having the cons-

  truction mentioned above satisfies the following conditions: (condition 1) 0.2 <fw / fI <0.6 (condition 2) 1.1 <fw / f12w <1.9 in which: fw: focal length combined with wide angle position level of the wide-angle zoom, fl: focal length of the first lens group, f12w: combined focal length of the first lens group and the second lens group at the wide angle r4 1 1 ( condition 3) 1.5 <x f2 xf <2, li = l (f2i x vd2j) j in which: f2i: focal length of the i lens of the second group of lenses II in the direction of the object, vd2i: the number of ABBEs of the ie lens of the second group of lenses II in the direction of the object, f2: focal length of the second group of lenses II According to another aspect of the present invention, the wide-angle zoom system comprises a

  first group of lenses and a second group of lenti-

  lenses with positive convergence and a third group of lenses with negative convergence. The distances between the first lens group, the second lens group, and the third lens group change while the zoom is operated. The

  first group of lenses has a first lens

  tille having a negative convergence, having the shape of a concave meniscus lens in the direction of a

  object, a second lens having a posi-

  tive and a third lens having a ne-

  gative. The first, second and third group of lenses are made up of spherical lenses. The

  distance between the first and second group of len-

  tilles is increased and the distance between the second and

  the third group of lenses is reduced.

  The wide-angle zoom system according to the cons-

  truction mentioned above satisfies the following condition: (condition 4) -0.5 <(Rla, + Rla2) / (Rl - Rua) <-2, in which:

  Rlal: radius of the curvature in the direction

  tion of the object of a lens layer from the first group of lenses,

  Rla2: radius of the curvature in the direction

tion of the image plan of the laie len-

  tille from the first group of lenses.

  In addition, the wide-angle zoom system according to the construction mentioned above also satisfies the following condition: (condition 5) 0.0 <(Ru> + Ru2) / (Ri, - R <) <2, 0 in which:

  Rl: radius of the curvature in the direction

  tion of the object of a lb 'i lens of the first group of lenses,

  Rb2: radius of the curvature in the direction

tion of the lbi m len- image plan

  tille from the first group of lenses.

  In addition, the wide-angle zoom system according to the construction mentioned above additionally satisfies the following condition: (condition 6) -6.0 <(R2dl + R2d2) / (R2dl - R22) <-2.5 in which

  R2Ul: radius of the curvature in the direction

  tion of the object of a second lens from the second group of lenses,

  R2d2: radius of the curvature in the direction

  tion of the image plan of 2diè- len-

tille from the second group of len-

  tilles. In addition, the wide-angle zoom system according to the construction mentioned above also satisfies the following condition: (condition 7) 9.0 <(t2c + t2d) <12.5 in which: t2c: thickness over l optical axis of a second lens from the second lens group, t2d: thickness on the optical axis of the second lens from the second lens group. In addition, the wide-angle zoom system according to the construction mentioned above also satisfies the following conditions: (condition 8) -0.20 <f3 / fT <-0.12 (condition 9) 1.05 <LT / fT <1.20 in which: LT: distance on the optical axis since

  plane of the lens located in the direction

tion of the object of the lens laie

  from the first group of lenses to the ni-

  calf from a telephotographic position

  wide-angle zoom to the image plane, fT: combined focal length at the telephoto position of the wide-angle zoom, f3: focal length of the third group

of lenses.

  Additional goals and benefits of

  present invention will appear on reading the

  cription which will follow, and, for a part, will become

  evident from the description, or can be

  covered by practicing the present invention.

  The objects and advantages of the present invention are realized

  read and reached through elements and

  combinations noted more particularly in the

appended vendications.

  The accompanying drawings, which are incorporated into

  part of this description and constitute

  part, represent embodiments of the

  present invention and, associated with the description, serve

  to explain the principles of the present invention. In these drawings: - Figure 1 is a sectional view of a zoom

  wide-angle at a wide-angle position, se-

  lon a preferred embodiment of the present invention

  tion, - Figure 2 is a sectional view of a wide-angle zoom at a middle position, according to a preferred embodiment of the present invention, - Figure 3 is a sectional view of a zoom wide angle at a telephoto position,

  according to a preferred embodiment of the present in-

vention,

  - Figure 4 shows the amplitude of the aber-

  spherical rations associated with the zoom at the level of a

  wide-angle view, according to a first preferred embodiment of the present invention,

  - Figure 5 shows the amplitude of the as-

  tigmatism associated with the zoom at a wide-angle position, according to a first preferred embodiment of the present invention,

  - Figure 6 shows the amplitude of the dis-

  torsion associated with the zoom at a wide-angle position, according to a first preferred embodiment of the present invention,

  - Figure 7 shows the amplitude of the aberr-

  spherical ration associated with the zoom at a position

  telephotography, according to a first preferred embodiment of the present invention,

  - Figure 8 shows the amplitude of the as-

  tigmatism associated with the zoom at a position of

  telephotography, according to a first preferred mode of realization

sation of the present invention,

  - Figure 9 shows the amplitude of the dis-

  torsion associated with the zoom at a teposition position

  ephotography, according to a first preferred embodiment

  tion of the present invention, FIG. 10 represents the amplitude of the spherical aberration associated with the zoom at a wide-angle position, according to a second preferred embodiment of the present invention,

  - Figure 11 shows the amplitude of the as-

  tigmatism associated with the zoom at a wide-angle position, according to a second preferred embodiment of the present invention, - Figure 12 shows the magnitude of the distortion associated with the zoom at a position of

  wide-angle, according to a second preferred embodiment

  tion of the present invention, - Figure 13 shows the magnitude of the spherical aberration associated with the zoom at a

  telephotography position, according to a second pre-

  fairy of realization of the present invention,

  - Figure 14 shows the amplitude of the as-

  tigmatism associated with the zoom at a position of

  telephotography, according to a second preferred mode of

  Lisation of the present invention, - Figure 15 shows the magnitude of the distortion associated with the zoom at a position of

  telephotography, according to a second preferred mode of

  reading of the present invention, FIG. 16 represents the amplitude of the spherical aberration associated with the zoom at a wide-angle position, according to a third preferred embodiment of the present invention,

  - Figure 17 shows the amplitude of the as-

  tigmatism associated with the zoom at a position of

  wide-angle, according to a third preferred embodiment

  tion of the present invention, - Figure 18 shows the magnitude of the distortion associated with the zoom at a position of

  wide-angle, according to a third preferred embodiment

  tion of the present invention, - Figure 19 shows the magnitude of the spherical aberration associated with the zoom at a telephoto position, according to a third preferred embodiment of the present invention, - Figure 20 shows the magnitude of the astigmatism associated with the zoom at a position of

  telephotography, according to a third preferred mode of

  reading of the present invention, FIG. 21 represents the amplitude of the distortion associated with the zoom at a position of

  telephotography, according to a third preferred mode of

  reading of the present invention, FIG. 22 represents the amplitude of the spherical aberration associated with the zoom at a wide-angle position, according to a fourth preferred embodiment of the present invention,

  - Figure 23 represents the amplitude of the as-

  tigmatism associated with the zoom at the level of a position of

  wide-angle, according to a fourth preferred embodiment

  tion of the present invention, - Figure 24 shows the magnitude of the distortion associated with the zoom at a position of

  wide-angle, according to a fourth preferred embodiment

  tion of the present invention, FIG. 25 represents the amplitude of the spherical aberration associated with the zoom at a telephoto position, according to a fourth preferred embodiment of the present invention,

  - Figure 26 shows the amplitude of the as-

  tigmatism associated with the zoom at a position of

  telephotography, according to a fourth preferred mode of

  reading of the present invention, FIG. 27 represents the amplitude of the distortion associated with the zoom at a position of

  telephotography, according to a fourth preferred mode of

of the present invention.

  We will now refer in detail to

  preferred embodiments of the present invention

  tion, examples of which are shown in the accompanying drawings. Whenever possible, the same reference numbers are used throughout the drawings to

  indicate the same or similar parts.

  A wide-angle zoom system according to a preferred embodiment of the present invention comprises a first group of lenses I, a second group of lenses II, and a third group of lenses III which are arranged in this direction towards a object and

  separated from each other over predetermined distances

born.

  The wide-angle zoom system according to a preferred embodiment of the present invention comprises a first group of lenses I having positive convergence, a second group of lenses II having positive convergence and a third group of lenses III having negative convergence . The first group of

  lenses I has an ugly lens 1 having a con-

  negative vergence, in the form of a menis-

  that concave towards an object and a lbie lens 2 having positive convergence and a convex plane in

  direction of an image plane. The second group II of len-

  tilles has a 2aim lens 3 having two sides

  concaves, a 2bi lens 4 having a po- convergence

  sitive and coming into abutment against the second lens 3, a second lens 5 having two convex sides, a second lens 6 having a negative convergence having the shape of a meniscus lens and coming into abutment

  2ci 'lens 5, a 2eTM lens 7 having a conver-

  positive gence and a second lens 8 having a convergence

  negative agency. The third group of lenses III com-

  wears a 3ai lens 9 having a positive convergence

  tive, a 3búi lens 10 having a negative convergence

  tive and concave in the direction of the object, and a 3ci lens 11 having a negative and concave convergence in the direction of the object. A diaphragm is mounted between the second group of lenses II and the third group of

lenses III.

  According to another embodiment of the pre-

  invention, the distance between the first group of lenses I and the second group of lenses II is

  increased and the distance between the second group of len-

  tilles II and the third group of lenses III is re-

  pick to increase the overall focal length of the lens

  jective. So variations in magnification from

  from a wide-angle position to a tele-position

  photographs are taken while the first group of lenses I, the second group of lenses II, and the

  third group of lenses III move in the direction

tion of an object.

  Wide-angle zoom in another preferred mode

  of the present invention comprises a pre-

  mier group of lenses having a positive convergence,

  a second group of lenses having a ne-

  gative, and a third group of lenses having positive convergence towards an object. The first group of lenses I comprises a first lens

  having a negative convergence, having the form of a slow

  tille meniscus concave towards an object. The third

  sth lens group has a short focal length

  negative and all lenses consist of len-

  spherical pins. As a result, this lens provides sufficient rear focal length to mount a

  panoramic photographic system at the posi-

  wide-angle tion. This objective also allows

  kill a telephoto type lens system at the level

  from a telephoto position, thus making com-

pact wide-angle zoom.

* The operation of the conditions mentioned

  above will be described in detail below.

  Condition 1 concerns the combined lateral magnification of the second group of lenses II and of the

  third group of lenses III at the posi-

  widest angle to get a zoom ratio

  at high magnification while maintaining good per-

  aberration level training.

  If the focal length ratio of the condi-

  tion 1 exceeds the upper limit, the length at ni-

  calf of the optical axis of the entire optical system (the full field of the lens) at the position

  of the largest angle becomes short, but the aberration of-

  is important because the rear focal length is shortened and the light passing through the

  second group of lenses II passes through a posi-

  higher or lower than the optical axis of the third

  sth group of lenses III. In addition, the curvature of a

  image plane becomes important and a chromatic aberration

  that appears from the fact that the sum of Petzval intended to compensate concurrently for the astigmatism of the objective and

  the curvature of the image is compensated excessively

sive.

  If the ratio of the focal lengths of the con-

  dition 1 falls below the lower limit it's

  easy to compensate for the aberration, but the length at ni-

  calf of the optical axis of the optical system as a whole

  ble at the wide-angle position becomes too

  important to achieve compactness.

  Condition 2 concerns the focal length

  of the first group of lenses I and of the second group of lenses II. If condition i is satisfied, the focal length of the second lens group is

  determined by condition 2 to compact the system

  optic as a whole at the position

wide-angle.

  If the ratio of the focal lengths of the con-

  dition 2 exceeds the upper limit, the length, at

  level of the optical axis, of the optical system in its

  seems (the entire field of the lens) becomes short, but the curvature of the image plane becomes large and a chromatic aberration appears because the

  Petzval sum is over-compensated.

  If the ratio of the focal lengths of the con-

  dition 2 falls below the lower limit of the range, it is easy to compensate for aberrations, but

  the overall rear focal length of the optical system from-

  is large and the outside diameter of the third group of lenses III becomes large because the length, at the optical axis, of the optical system as a whole becomes large and the length

  focal length of the third group of lenses III becomes im-

bearing.

  Condition 3 concerns the compensation for the aberrations that appear around the image plane. In

  in particular, chromatic aberrations when the dis-

  tance existing between the second group of lenses II

  and the third group of lenses III increases at the ni-

  calf from the wide-angle position in the constituted zoom

  of the first group of lenses having a po-

  sitive, of the second group of lenses having a conver-

  negative gence, and of the third group of lenses having

  positive convergence towards the object.

  If a value exceeds the upper limit or falls below the lower limit of the condition

  3, color dispersion is caused even when

  that a photograph is taken by closing a slide

  phrasing, of the fact that generic aberrations, like the

  magnification of chromatic aberrations, are

  born beyond the optical axis on the image plane at the level

  from the wide-angle position and it's hard to understand

  think of the chromatic aberrations for the color wavelengths, i.e. the C radiation and the ra-

  diation E among chromatic aberrations.

  Condition 4 concerns a form factor which

  defines the shape of the lens lay. If a value

  passes the upper limit of condition 4, the conversion

  gence of the lens laià becomes strong, thus making

  it is difficult to compensate for aberrations, and if the value falls below the lower limit of the con

  4th edition, the convergence of the second lens becomes

  low, making it difficult to get the length fo-

sufficient rear wedge.

  Condition 5 concerns the definition of

  shape of the lens lbi. If a value exceeds the limit

  upper mite of condition 5, the radius of curvature

  of the lbi 'lens becomes small, resulting in

  higher degrees of aberration. In addition, if the value falls below the lower limit of condition 5, the radius of curvature of the lens lbi'me

  becomes important, making it difficult to compensate

  sation of the aberrations and the focal length of the first

  lens group I becomes important, making diffe-

  difficulty obtaining a compact camera.

  Condition 6 concerns the definition of

  shape of the 2di "lens. If a value exceeds the li-

  upper mite of condition 6, chromatic aberrations

  are over-compensated, making

  thus important the remaining chromatic aberrations.

  In addition, if the value falls below the lower limit

  of condition 6, the radius of curvature of the len-

  tilts towards the object becomes small and the conver-

  gence of the 2nd lens becomes weak, consequently leading to higher degree aberrations and making it difficult to compensate for chromatic aberrations. The second lens and the second lens are lenses in abutment and compensate for the chromic aberrations, and on the other hand, compensate for the curvature of

  the image by constructing a concentric field.

  As a result, if a value exceeds the upper limit of condition 7, the thickness of the second lens group II becomes large, thereby making it difficult to obtain a compact camera and the amount of light around the object is

  scaled down. In addition, if the value falls below the limit

  condition 7 lower moth it's hard to

  construct the concentric field, thus making it diffi-

  cile compensation for the curvature of the image.

  Conditions 8 and 9 concern the creation of a compact lens system. If a value exceeds the upper limit of conditions 8 and 9, the convergence

  of the third group of lenses III becomes strong and this-

  this is advantageous for making the objective system com-

  pact, but it is difficult to compensate for the higher degrees of aberration occurring when the radius of curvature of the lens surface becomes small. Of

  more, if the value falls below the lower limit

  conditions 8 and 9, it is difficult to make

  compacts the lens system for image curvature.

  Tables 1, 2, 3 and 4 show the values

  for a first, a second, a third, and a qua-

  third embodiment of the present invention. The optical characteristics of the first, second,

  third, and the fourth embodiment are re-

  shown in Figures 4 to 27.

  In the following tables, f is the longest

  focal length, ri (i = i to 20) is the radius of curvature

  of a refraction plane i, di (i = 1 to 20) is the thick-

  sor of the lens or the distance between lenses, N is the refractive index of the line d of the lens, vd

  is the ABBE number of the lens, m is the magnification

  ment of the lens system as a whole and w is half the angle of view. The distances are given in nMR.

  Values meeting the men-

  mentioned above in accordance with the first preferred embodiment of the present invention are given in

  the array i in which a number F, i.e. the lu-

  minance Fno is from 3.8 to 10.25, the focal length f is from 29.012 mm to 86.971 mm, the half-angle of view w is from 36.61 to 13.8, and the rear focal length fb is from

8.5 mm to 54.076 mmn.

TABLE 1

  surface number r d N vd i -26, 814 1.80 1.84666 23.78

2 -45.966 0.10

3,247.331 3.50 1.62041 60.34

4 -30.106 2.4 to 10.35

-18.046 0.85 1.78590 43.93

6 7.977 3.29 1.72825 28.32

7 -119.902 0.10

8 20.655 4.37 1.51680 64.20

9 -8.976 6.40 1.83400 37.34

-13.847 0.10

11 34.184 2.50 1.51680 64.20

12 -12.808 0.80 1.84666 23.78

13 -33,350 1.20

14 9.50 to 1.56

387.524 3.05 1.75520 27.53

16 -16,752 0.10

17 -23.738 1.00 1.77250 49.62

18 92.829 3.65

19 -11.093 1.20 1.75700 47.71

-382,204

  The values of the conditions described in the

  conditions 1 to 9 according to the first preferred mode of realization

  sation are: (condition 1) fw / fl = 1.486 (condition 2) fw / fl2w = 0.340 r 4

1 1

  (condition 3) 1 x f2 xf, = 2.535 Li = l (f2i x vd2i) j (condition 4) (Ral + Rla2) / (Ral - Rla2) = -3.800 (condition 5) Rlb, + Rb2) / Rlbl - Rlb2) = 0.783 (condition 6) (R2dl + R2d2) / (R2d1 - R2d2) = -4.685 (condition 7) (t2c + t2d) = 10.700 (condition 8) f3 / fT = -0.201 (condition 9) LT / fT = 1.150 The optical characteristics of the first preferred embodiment are shown in the figures

4 to 9.

  The values satisfying the conditions mentioned-

  born above in accordance with the second preferred embodiment of the present invention are given in table 2 o a number F, that is to say the luminance Fno is from 3.7 to 10.26, the focal length f is from 29.016 mm at 86.73 numm, the half-angle of view w is from 37.08 to 13.91, and the rear focal length fb is from 8.483 mm

at 56.38 mm.

TABLE 2

surface number r d N vd

1 -26.220 1.15 1.84666 23.78

2 -63.280 0.10

3,173.961 3.40 1.58913 61.25

4 -26,734 2.89 to 8.63

-15.939 0.85 1.80420 46.50

6 9.301 3.08 1.72825 28.32

7 -56.838 0.37

8 21.385 3.86 1.51823 58.96

9 -7.731 6.10 1.78590 43.93

-12.206 0.10

11 32,850 2.80 1.51680 64.20

12 -11.482 0.80 1.84666 23.78

13 -34,500 1.20

14 0 9.07 to 1.57

-82.495 2.90 1.80518 25.46

16 -16,650 0.10

17 -22.913 1.00 1.62299 58.12

18 62.210 3.89

19 -10.996 1.20 1.75700 47.71

-89,150

  The values of the conditions described in the

  conditions 1 to 9 according to the second preferred mode of realization

  sation are: (condition 1) fw / fI = 1.535 (condition 2) fw / fl2w = 0.323 r4 1 1 (condition 3) x f2 x fw 2.435 Li = l (f2i x vd2i) xf (condition 4) RIa, + Rla2 ) / (RIa - R1a2) -2.716 (condition 5) Rjbi + Rlb2) / IRb - Rlb2) 0.734 (condition 6) R2dI + R2d2) / R2d - R2d2) = -4.455 (condition 7) t2C + t2d) = 9.960 ( condition 8) f3 / fT = -0.199 (condition 9) LT / fT = 1.160 The optical characteristics of the second preferred embodiment are shown in the figures

at 15.

  The values satisfying the conditions mentioned-

  born above in accordance with the third preferred embodiment of the present invention are given in table 3 o a number F, that is to say the luminance Fno is from 3.7 to 10.3, the focal length f is 28.998 mm to 86.868 mm, the half-view angle w is 36.72 to 13.85, and the rear focal length fb is 8.491 mm

at 53.477 mm.

TABLE 3

  surface number r d N vd i -27,696 1.80 1.80518 25.46

2 -42.929 0.10

3,196.461 2.22 1.63854 55.45

4 -30.051 2.40 to 8.69

-18.799 0.85 1.83400 37.34

6 8.349 4.55 1.72825 28.32

7 -44.166 0.10

8 20.127 5.39 1.51823 58.96

9 -9.729 6.00 1.83400 37.34

-14.594 0.10

11 43.443 2.50 1.51680 64.20

12 -13.099 0.80 1.84666 23.78

13 -29.593 1.20

14 7.85 to 1.56

94.437 2.94 1.72825 28.32

16 -16.503 0.10

17 -22,748 1.00 1.77 250 49.62

18 32.976 4.36

19 -9.169 1.20 1.75700 47.71

-37,885

  The values of the conditions described in the

  conditions 1 to 9 according to the second preferred mode of realization

  sation are: (condition 1) fw / fl = 1.611 (condition 2) fw / fl2w = 0.265 r4 1 i 1 (condition 3) Ix f2 x fw '2.308 Li = l (f2i x vd2i) J (condition 4) Rlal + Rla2) / (Rla - R1a2 / = -4, 636 (condition 5) RlbI + Rlb2) / (Rlb - Rlb2) = 1.361 (condition 6) R2d1 + R2d2) / (R2dl - R2d2) = -5,000 (condition 7) t20 + t2d) = 11.39 (condition 8) f3 / fT = -0.175 (condition 9) LT / fT = 1.139 The optical characteristics of the third preferred embodiment are shown in the figures

16 to 21.

  The values satisfying the conditions mentioned-

  born above in accordance with the fourth preferred embodiment of the present invention are given in table 4 o a number F, that is to say the luminance Fno is from 3.7 to 8.48, the focal length f is 29.003 mm to 77.963 mm, the half-view angle w is 36.87 to, 280, and the rear focal length fb is 8.499 mm

at 46.963 mmn.

TABLE 4

surface number r d N vd

1 -31.681 1.80 1.84666 23.78

2 -68.852 0.10

3 69.639 3.50 1.75700 47.71

4 -43.292 2.4 to 10.35

5 -21.561 0.85 1.78590 43.93

6 8.773 3.29 1.72825 28.32

7 -165.519 0.10

8 32.654 4.37 1.62041 60.34

9 -8.704 6.40 1.84666 23.78

10 -18.373 0.10

11 94.705 2.50 1.51680 64.20

12 -30.264 0.80

13 9.93 to 1.56

14 -71.261 2.99 1.64769 33.84

15 -14.261 0.10

16 -18.832 1.00 1.60311 60.69

17 -102.715 2.97

18 -11.668 1.20 1.74330 49.22

19,753,326

  The values of the conditions described in the

  conditions 1 to 9 according to the third preferred mode of reaction

  readings are: (condition 1) fw / fl = 1.462 (condition 2) fw / f12w = 0.439 r4 1 1 (condition 3> 1Li = 1 (f2i X Vd2i) 1 (condition 4) Rlal + Rla2) / (Rla1 - Rla2 ) = -2.706 (condition 5) Rlb + Rlb2) / (Rlb - Rlb2) = 0.233 (condition 6) R2dI + R2d2) / (R2d1 - R2d2) = -2.80 (condition 7) t2d + t2d) = 10.770 ( condition 8) f3 / fT = -0.243 (condition 9) LT / fT = 1.189 The optical characteristics of the fourth preferred embodiment are shown in the figures

22 to 27.

  As described above, in the preferred embodiment of the present invention there is provided a wide-angle zoom system which can reduce the variation of aberrations and obtain a sufficient back focal distance at the wide-angle position by making the angle of view important at the wide-angle position and by making the total length of the short

  optical system at the telephotographic position

  phie. The first group of lenses includes the conversion

  negative gence using the lens shape

  that concave towards an object and the lens having

  a positive convergence in the zoom made up of the first

  mier group of lenses having a positive convergence.

  The second group of lenses has negative convergence

  tive, and the third group of lenses has a conver-

  positive direction towards an object. The zoom can

  think the aberrations beyond the optical axis, in par

  especially generic aberrations analogous to magnification

  chromatic aberration by assembling lenses and adjusting the focal length of each

  lens correctly in the second group of len-

tilles.

  Other embodiments of the present in-

  vention will appear to those skilled in the art considering the

  description and application of this invention

  tion described here. It is expected that the description and

  examples to be considered as an example only, the true scope and spirit of the present invention

  being indicated by the appended claims.

  For example, the embodiments of the pre-

  sente invention use 35mm film format

  while other lenses intended for different formats

* different and different applications can be carried out in accordance with the present invention. Furthermore,

  the objectives according to the present invention are not limited to

  mapped to lens shutter cameras but can also be used with other

  cameras such as cameras

  focal plane shutter graphics.

Claims (6)

  1. Zoom system comprising: a first group of lenses (I) having a positive convergence, a second group of lenses (II) having a positive convergence, and a third group of lenses (III) having a negative convergence, the distances between the first group of lenses, the second group of lenses, and   the third group of lenses changing during the zoom operation,   characterized in that the first group of len-   tilles comprises: a first lens (1) having a negative convergence in the form of a concave meniscus lens in the direction of the object, a second lens (2) having a positive convergence and a third lens having a negative convergence, the first , the second and the third group of lenses being made up of spherical lenses, the distance existing between the first and the second group of lenses is increased, and the distance between the   second and third lens group is dimi- cloud, and   in that the zoom system has the characteristics   following ticks: -0.5 <(Rla + Rla2) / (Ri l - Ras) <-2, in which Rlal is the radius of curvature   in the direction of the object of a lai "lens of the pre-   mier group of lenses, R1a, 2 is the radius of curvature in the direction of the image plane of a lens line of the first group of lenses. 2. Zoom system according to claim 1, characterized in that it also has the following characteristics: 0.0 <(R + R2) / (R - RD2) <2.0   in which Ribi is the radius of curvature   in the direction of the object of a lb lens of the first   mier group of lenses, and Rb2 is the radius of curvature in the direction of the image plane of the lbth lens of the first group of lenses.   3. Zoom system according to claim 1,   characterized in that the first group of lenses door:   a lens line with negative convergence   tive in the form of a concave meniscus lens di- erection of an object, and   a lbTM lens with positive convergence   tive and a convex plane in the direction of an image plane, the second group of lenses (II) comprises: a second lens having two concave sides,   a 2bie lens with positive convergence   tive and coming into abutment against the 2a lens, a 2ci lens having two convex sides,   a 2di lens with negative convergence   tive in the form of a meniscus lens and coming into abutment with the 2c lens,   a second lens having a positive convergence tive, and   a 2fi lens with negative convergence   tive, the third group of lenses (III) having negative convergence, the distance existing between the first group of   lenses and the second group of lenses is increased   tee and the distance between the second lens group and the third lens group III is reduced, thereby generating variations in magnification from a wide-angle position to a telephoto position taken while the first group of   lenses, the second group of lenses, and the third   sth group of lenses (III) move towards an ob-   jet during zoom actuation from the position   wide-angle to the telephoto position, and   in that the zoom system has the characteristics   following ticks: -6.0 <(R2dl + R2d2) / (R2 - R2d2) <-2.5 in which R2dl is the radius of curvature in the direction of the object of a 2nd lens from the second group of lenses, R2d2 is the radius of curvature in the direction of the image plane of the 2nd lens of the second group of lenses.   4. Zoom system according to claim 3, characterized in that the first, the second, and the   third group of lenses consist of len- spherical pins.   5. Zoom system according to claim 3, characterized in that it also has the following characteristics: 9.0 <(t2c + t2d) <12.5 in which t2c is the thickness on the axis   optics of a 2c i 'lens of the second group of len-   tilles, and t2d is the thickness on the optical axis of a   2d lens of the second group of lenses (II).   6. Zoom system according to claim 1,   characterized in that the first group of lenses door:   a lai & M lens with negative convergence   tive in the form of a concave meniscus lens di- erection of an object, and   a lbiàm lens having a posi-   tive and a convex plane towards an image plane,   a second group of lenses with a con-   positive vergence and in that the third group of lenses (III) comprises:   a 3rd lens having a positive convergence tive,   a 3bie lens with negative convergence   tive and concave towards the object, and   a 3cie lens with negative convergence   tive and concave towards the object, and   in that the zoom system has the characteristics   following ticks: -0.20 <f3 / fT <-0.12 1.05 <LT / fT <1.20 in which f3 is the focal length of the third group of lenses,   fT is the focal length combined at ni-   calf from the telephoto position of the large zoom angle, and   LT is the distance on the optical axis from   shot from the plane of the lens located in the direction of the ob-   jet of the laià lens of the first group of lenses at a telephoto zoom position wide-angle to the image plane.